Presently, a two-stage dust collecting device is available in the market which separates dust filtered from dust-laden air into coarse and fine dust portions and which collects the coarse and fine dust portions at different sites. A conventional two-stage dust collecting device includes a primary dust collecting container, a secondary dust collecting container disposed proximate to the primary dust collecting container, and a mounting cover disposed to cover sealingly an open upper end of the primary dust collecting container. The mounting cover has a mounting major wall with a peripheral portion, an inlet disposed in the mounting major wall for introducing the dust-laden air so as to collect the coarse dust portion in the primary dust collecting container, and an outlet disposed in the mounting major wall and spaced apart from the inlet and in communication with the secondary dust collecting container so as to draw out the fine dust portion from the primary dust collecting container. A blower is disposed downstream of the outlet to draw the fine dust portion for storage in the secondary dust collecting container. A filtering member is disposed upstream of the outlet to admit entrance of only the fine dust portion into the secondary dust collecting container via the outlet.
A drawback of the aforesaid dust collecting device resides in that the primary dust collecting container is bulky and is thus inconvenient to transport and store.